Budding envelopes of certain commercial and mixed use residential buildings include a curtain wall. The curtain wall of a building defines the appearance of the budding and, more importantly, separates the interior controlled or conditioned space from the outside environment. The curtain wall is usually formed from a plurality of curtain wall panels that typically contain glass, metal, and/or stone. The curtain wall panels are attached to the building's structural elements via anchors and curtain wall panel hanging brackets (sometimes referred to as curtain wall panel brackets or panel brackets). The anchors are located at discrete attachment points along the edges of the building's concrete floor slabs. The anchors typically include embedments (sometimes referred to as embeds) that are each cast into a concrete floor slab and that may be located on the top of the slab, on the face of the slab, or beneath the slab. A panel bracket is attached to each embedment, and a curtain wall panel is hung from each panel bracket.
For a given concrete floor slab, before the concrete that forms that concrete floor slab is poured into the concrete form, an array of rebar, metallic cables, and/or other material used to reinforce the concrete floor slab is installed within the concrete form. Embedments are then positioned along an edge of the concrete form by a worker using a tape measure and control lines provided by the general contractor. That is, the worker typically uses the tape measure to hand measure where to position each embedment along the edge of the concrete form using the control lines for reference, though in certain instances the embedments are positioned along the edge of the concrete form with the aid of survey equipment.
This installation process requires another measurement by the worker to assure the embedment has the proper edge spacing from the concrete form (i.e., to ensure the embedment is located at the proper distance from the edge of the concrete form). More specifically, after determining the position along the edge of the concrete form at which to attach the embedment, the worker must then use the tape measure to hand measure the distance of the embedment from the edge of the concrete form. The worker then anchors the embedment into place by either nailing the embedment to the concrete form, wire tying the embedment to rebar, or wire tying the embedment to scraps of lumber and then nailing the lumber to the concrete form such that the anchored embedment has the proper edge spacing from, and is positioned at the desired position along the edge of, the concrete form.
Concrete is then poured into the concrete form, typically via a high pressure concrete pumping hose. Concrete pumping hoses are heavy and unwieldy, and typically require multiple workers to control and operate the concrete pumping hose while walking on and around the rebar, metallic cables, and/or other reinforcing materials within the concrete form. As and after the concrete is being poured (pumped) into the concrete form, several workers level the poured concrete, which again involves the workers walking on and around the rebar, metallic cables, and/or other reinforcing materials. This movement, shifting, and jostling of the rebar, metallic cables, and/or other reinforcing materials, along with the vibration of the concrete pumping hose and the movement of the poured concrete itself, is problematic because it may alter the position of one or more of the embedments or dislodge one or more of the embedments.
Sometime after the concrete has been poured, each embedment must be located and exposed, which sometimes requires workers to chip away any concrete that may be covering the embedment. After the embedments are located and exposed, a survey is conducted to determine whether any of the embedments are potentially problematic. More specifically, the survey is conducted to determine whether any embedments are missing, any embedments are buried too deep within the concrete floor slab, any embedments are improperly positioned or misaligned, and/or whether any embedments conflict with other features of the budding. After the survey is completed, any problematic embedments must be fixed before panel brackets are attached. For example, if an embedment is missing, is buried too deep within the concrete slab; is improperly positioned or misaligned, or conflicts with another feature of the building, a panel bracket may not be able to be properly mounted to that embedment. In such a case, mounting hardware for the panel bracket must be secured directly to the concrete floor slab by post-drilling into the concrete floor slab and securing the mounting hardware via wedge bolts and/or chemical bonding.
After any problematic embedments are fixed, a panel bracket is attached to each embedment using fasteners. For each floor of the building, the panel brackets on that floor are leveled relative to one another such that they are all planar and at a proper elevation so the installed curtain wall panels will be level and properly spaced relative to one another. The curtain wall panels are then individually hoisted into their respective final positions using a tower crane, truck crane, or mini crane.
The process of installing the embedments can result in a variety of problems caused by human error. Specifically, human error in measuring the distance from the embedment to the edge of the concrete form and/or in attaching the embedment to the form can cause the embedment to be improperly spaced from the edge of the concrete form (i.e., to not have the proper edge spacing). Additionally, once the embedments are positioned and attached to the concrete form, the embedments are inherently unstable before and during the pouring of concrete into the concrete form and the leveling of the poured concrete. For instance, if a worker bumps into or steps on the embedment or the reinforcing material to which the embedment is attached, the embedment could be moved out of place such that it no longer has the proper edge spacing or is dislodged entirely. Further, the embedments can be covered with concrete during pouring, requiring a worker to chip away cured concrete to uncover each embedment. Additionally, the process of attaching a panel bracket to each embedment is labor intensive, expensive, and time consuming.
There is a need for new apparatuses and methods for positioning embedments at the proper edge spacing from the concrete form that solve the above problems.